Cassette tape decks are commonly used in automobiles. While in automobiles, they are subject to theft or to misuse. The tape deck, or similar equipment, is operable by inserting a cassette or CD or floppy disk into the receiving chamber through an opening. Providing the electric power is connected, there is nothing to stop any person from operating the equipment.
Cassette tape decks and similar equipment are portable and usually easily removed from their mountings. They are thus relatively easy to steal and resell. If an installed device prevented easy use of the equipment without damage, it could act as a deterrent to theft.
A number of cassette tape deck locking devices and similar devices have been invented and are available. Among these are U.S. Pat. No. 4,655,057 by Jay S. Derman, U.S. Pat. No. 4,640,106 by Jay S. Derman and U.S. Pat. No. 4,131,001 by Raymond J. Gotto. U.S. Pat. No. 4,655,057 utilizes a member to cover the cassette chamber opening and has inward projecting arms that impinge on the opened chamber door, securing the device in a blocking position. Rotating a built-in lock element by means of a key, unlocks the device by lifting the door from its engagement with the projecting arms. U.S. Pat. No. 4,640,106 utilizes a member to cover the cassette chamber opening and a "U" shaped body bolt together with a threaded rod for insertion in the cassette chamber. The threaded rod is rotated by a cylinder lock and an adjustable position lock element is moved to block removal of the locking device from the chamber.
U.S. Pat. No. 4,131,001 utilizes a cassette-shaped part for insertion in the cassette chamber opening. By means of gears that are connected to a lock cylinder, projecting arms and locking members are moved to impinge against the inside chamber surfaces preventing removal of the locking device.
The first discussed device, U.S. Pat. No. 4,655,057 is relatively simple in construction. It depends entirely on interaction with the cassette chamber door, which prevents the device from being withdrawn unless it is unlocked. It requires the use of a built-in cylinder lock to rotate the unlocking device. An external padlock cannot be used in its place.
The remaining two devices are both relatively complex in concept and in construction. As for the first device, both require the use of a built-in cylinder lock to both lock and unlock the device. An external padlock cannot be used.
Other proposed locking devices utilize housings for enclosing the cassette tape deck or similar equipment, providing a concealed limited access keyway for locking the equipment to the automobile dashboard or cabinet.